(a) Would you expect stearic acid, \(\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{16} \mathrm{COOH},\) to be more soluble in water or in carbon tetrachloride? Explain.

Stearic acid has a polar carboxylic acid group (-COOH) and a long nonpolar hydrocarbon chain. The majority of the molecule is nonpolar since the long hydrocarbon chain greatly outnumbers the single polar carboxylic acid group. Therefore, we can consider stearic acid to be predominantly nonpolar.

Water is a polar solvent because of the difference in electronegativities between hydrogen and oxygen atoms. The presence of hydrogen bonding in water results in a strong polar nature. Carbon tetrachloride, \(\mathrm{CCl}_{4}\), is a nonpolar solvent since it has a symmetrical tetrahedral structure with equal distribution of electronegativity among the chlorine atoms.

Since stearic acid is predominantly nonpolar and the principle "like dissolves like" states that nonpolar substances are more likely to dissolve in nonpolar solvents, we can conclude that stearic acid will be more soluble in carbon tetrachloride than in water.

In water, stearic acid would experience weak dispersion forces with the water molecules due to the nonpolar hydrocarbon chain, which is insufficient to overcome the strong hydrogen bonding in water. Thus, stearic acid is not very soluble in water. However, in carbon tetrachloride, the dispersion forces between stearic acid and the solvent molecules are much stronger, which allows stearic acid to dissolve more readily in carbon tetrachloride. (a) Stearic acid will be more soluble in carbon tetrachloride than in water because the majority of its structure is nonpolar, which makes it more compatible with the nonpolar solvent. This is due to the principle "like dissolves like" and the intermolecular forces present between stearic acid and the solvents.